Oct 20, 2022 · Oct 18, 2022 · Oct 19, 2022 · Oct 19, 2022
diff --git a/DIRECTORY.md b/DIRECTORY.md
  * [RodCutting](Dynamic-Programming/RodCutting.js)
  * [Shuf](Dynamic-Programming/Shuf.js)
  * [SieveOfEratosthenes](Dynamic-Programming/SieveOfEratosthenes.js)
  * [UniquePaths](Dynamic-Programming/UniquePaths.js)
  * **Sliding-Window**
    * [LongestSubstringWithoutRepeatingCharacters](Dynamic-Programming/Sliding-Window/LongestSubstringWithoutRepeatingCharacters.js)
    * [PermutationinString](Dynamic-Programming/Sliding-Window/PermutationinString.js)
diff --git a/Dynamic-Programming/UniquePaths.js b/Dynamic-Programming/UniquePaths.js

 /*
 *
 *  Unique Paths
 *
 *  There is a robot on an `m x n` grid.
 *  The robot is initially located at the top-left corner.
 *  The robot tries to move to the bottom-right corner.
 *  The robot can only move either down or right at any point in time.
 *
 *  Given the two integers `m` and `n`,
 *  return the number of possible unique paths that the robot can take to reach the bottom-right corner.
 *  More info: https://leetcode.com/problems/unique-paths/
 */

 /*
 * @param {number} m
 * @param {number} n
 * @return {number}
 */

 const uniquePaths = (m, n) => {
  // only one way to reach end
  if (m === 1 || n === 1) return 1

  // build a linear grid of size m
  // base case, position 1 has only 1 move
  const paths = new Array(m).fill(1)

  for (let i = 1; i < n; i++) {
    for (let j = 1; j < m; j++) {
      // paths[j] in RHS represents the cell value stored above the current cell
      // paths[j-1] in RHS represents the cell value stored to the left of the current cell
      // paths [j] on the LHS represents the number of distinct pathways to the cell (i,j)
      paths[j] = paths[j - 1] + paths[j]
    }
  }
  return paths[m - 1]
 }

 export { uniquePaths }
diff --git a/Dynamic-Programming/tests/UniquePaths.test.js b/Dynamic-Programming/tests/UniquePaths.test.js
 import { uniquePaths } from '../UniquePaths'

 describe('Unique Paths', () => {
  it('should return 28 when m is 3 and n is 7', () => {
    expect(uniquePaths(3, 7)).toBe(28)
  })

  it('should return 48620 when m is 10 and n is 10', () => {
    expect(uniquePaths(10, 10)).toBe(48620)
  })
 })
Original file line number	Diff line number	Diff line change
Expand Up		@@ -105,6 +105,7 @@
		* [RodCutting](Dynamic-Programming/RodCutting.js)
		* [Shuf](Dynamic-Programming/Shuf.js)
		* [SieveOfEratosthenes](Dynamic-Programming/SieveOfEratosthenes.js)
		* [UniquePaths](Dynamic-Programming/UniquePaths.js)
		* Sliding-Window
		* [LongestSubstringWithoutRepeatingCharacters](Dynamic-Programming/Sliding-Window/LongestSubstringWithoutRepeatingCharacters.js)
		* [PermutationinString](Dynamic-Programming/Sliding-Window/PermutationinString.js)
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,41 @@

		/*
		*
		* Unique Paths
		*
		* There is a robot on an `m x n` grid.
		* The robot is initially located at the top-left corner.
		* The robot tries to move to the bottom-right corner.
		* The robot can only move either down or right at any point in time.
		*
		* Given the two integers `m` and `n`,
		* return the number of possible unique paths that the robot can take to reach the bottom-right corner.
		* More info: https://leetcode.com/problems/unique-paths/
		*/

		/*
		* @param {number} m
		* @param {number} n
		* @return {number}
		*/

		const uniquePaths = (m, n) => {
		// only one way to reach end
		if (m === 1 \|\| n === 1) return 1

		// build a linear grid of size m
		// base case, position 1 has only 1 move
		const paths = new Array(m).fill(1)

		for (let i = 1; i < n; i++) {
		for (let j = 1; j < m; j++) {
		// paths[j] in RHS represents the cell value stored above the current cell
		// paths[j-1] in RHS represents the cell value stored to the left of the current cell
		// paths [j] on the LHS represents the number of distinct pathways to the cell (i,j)
		paths[j] = paths[j - 1] + paths[j]
		}
		}
		return paths[m - 1]
		}

		export { uniquePaths }
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,11 @@
		import { uniquePaths } from '../UniquePaths'

		describe('Unique Paths', () => {
		it('should return 28 when m is 3 and n is 7', () => {
		expect(uniquePaths(3, 7)).toBe(28)
		})

		it('should return 48620 when m is 10 and n is 10', () => {
		expect(uniquePaths(10, 10)).toBe(48620)
		})
		})